Coil coupler for radio receiving apparatus



June 5, 1934.

F. M. FREDERIKSEN conJ COUPLER FoRRADIo RECEIVING APPARATUS Filed June 8. 4,1952

Patented une v, `1934 COIL COUPLER FOR RADIO 'RCIVING APPARATUS Frederik Marius Frederiksen, Skorpingl', f

Denmark Application June 8, 1932, Serial No'. 616,151

In Denmark September 3, 1931 3 Claims. (Cl. 171-119) For tuning radio receivingapparatus to Wave lengths between 200 and 2000 meters, the present range ofradiophony, use ,is made of variable condensers. If a condenser having -an area of 5 450 centimeters is used, the number of windings of an associated inductance coil should be varied from'60 to 4about 260.

In so e Aof the apparatus hitherto known two coils are used, one for long and. one for short \waves, and the apparatus is then provided with a commutator. 'Ihis arrangement" involves a drawback, as an apparatus with, only two coils cannot be adjusted to all lengths of waves between 200 and 2000 meters. This drawbackhas been evaded in' the-,presl Aent invention, .which relates' to a coil coupler for radio receivers; in. which several sets of coil windings can Ibe coupled together in series, in parallel, and both in series and in parallel, by means of which it will always be possible to adjust the number of windings exactly to the wavelength wanted without putting loff or short-.circuiting any part of the coil.`

. An object of this 'invention is to providea device for changing-the .inductive coupling in a radio tuning circuit. f f\ Another object of thisv invetionisto devise a structure for. `changing the connections bef" tween a group of coils from series to parallel o r to series parallel.

In the drawing:

Figures-1, 2 and 3 show a coil coupler according to the invention in top view "and partly cut throughin .positions for long, medium an short lengths of waves, respectively.

Fig. 4 showsv a section on the line af-a in Fig.1. i The form of construction for'a 'coil coupler shown consists of a drum 5 of non-conducting l material which, by means of pivots 6, is rotatably mounted in bearingsf not shown in the drawing; so that the drum can `be rotated be- A tween two seriesof contact springs .7 to which the windings of thecoils are fixed.. These coils vare marked 8, 9, 10 and 11. i Through the ,drum

5 is inserted a seriesv of pins 12 (Fig. .1) and straps 13 (Fig. 2) of conducting material. Rails 14 (Figs. 2 and 3),'a1so of conducting material,

' are inserted in theA surface of the drum.

When the drum is in the position shown 'in Fig. 1, the pins 12 form electricconducting connections between two contact springs 7 placed opposite .to each other, by means rof which all Fig. '5 showsa section on the line b-b' in ofthe-coils 8-11 are joined up in series, which must take place when operating -with long waves. When the drum is rotated to the position shown in Fig. 2, pairs of contact springs '7, placed beside Leach other, are in touchv with the same bar or rail 14 and pairs of the coils are. connected in parallel. The several pairs of parallelly connected coils are ioined up in series by means of the straps 13 extending between opposite rails 14. This position is used for medium waves. If, finally, the drum is rotated toitheposition shown in Fig. 3, all of the contact springs, 7 placed at one side, to which the coils areconnected, contact with a single long rail or bar- 14, and all of the contact springs 7-of the other side, which are also in connection with the coils, contact with a similar opposite baror rail 14. Thus, all of the coils are joined up in parallel for the purpose of receiving short waves.

rIhe form of construction for a coil coupler shown in the drawing and described above is lintended to be used in connection with a doublev coil transformer, but the invention can also be arranged for a single coil and for a transformer Witha separate back-coupling coil.

By means of electric conducting lines 1, 2, 3 and 4, the coil coupler is connected with the rest .of the apparatus to antenna, ground, negative filament and grid,` respectively. In Fig. 1, itis shown how the line 1 through a line 15 is connected with a contact spring 16, which is in electric conducting connection with one of the. pivots 6 of the drum 5, which then at the same time forms'a shaft for the rotor of a rotary con'- denser, the stator of which is 1'7, to which the antenna can then be connected.

Several operationsrequire extraction from the {center of the coil. This is obtained in the form fof construction shown4 by connecting one end of the coil 9 to a. line 18 with a contact spring 19 which, in the couplings shown in Figs. 1 and 2, is in electric conducting connection through a strap 13 withanother contact spring 20, which is 'connected with a line 21, through which the extraction is made. l'

In the coupling shown in Fig. 3, where all of the coils 'are joined up in parallel, the contact,

spring 19 touches a button 22, which is not in center of a desired set of -windings with a contact spring 24, 'whichtogether with the contact spring 20 touches the same railpr bar 14.

In the form of constructionV shown, `four sets of windings are on each side of the transformer, but of course any other desirable number of sets of windings can be used.

4The sections connected to the left and right halves of the barrel in Figs. 1, 2 and 3 represent the secondary and primary sides of a transformer. respectively, so that the center extraction can be used either for neutrodyne stabilization or as antenna connection. 1f the coil coupler is to be used in rice-neutrodynes, the left y "half will be the primary and the right half with center extraction the secondary side. If an extra antenna connection is desirable here too, both halves of the transformer can be provided with center extractions.

The coil coupler can also be used for re` coupling o! a single coil, variable self-induction, tuned anode, in which case only one half of the barrel with its associated springs is required. The other half can then be used for the recoupling of an associated back coupling coil.

Figs. 4 and 5 show the cross-section of a possible form of construction for the coil coupler, the upper hatched part-showing the cross-section of the connected coil, while the lower part shows springs and barrel.

An essential advantage of the coil coupler described is that all of the windings connected with the coupler are in use for every wave length within the distance of wavelength of the coil in question. Thereby it will be possibleI to evade change oi coils in short wave apparatusv (under 200 meters).

I claim as my invention:-

1. A coil coupler for radio receiving apparatus comprising a plurality of coils, a rotary drum of insulating material, a plurality of diametricallyarranged contact elements associated with the drum; the ends of each coil being connected to a diametrically-positioned pair of said contact elements, a plurality of plugs extending through one diameter of the drum for conductively\ connecting opposed pairs of contact elements so that the coils are se'riall connected, a pluralityy of diametrically-oppose bars positioned on the surface ot the drum on another diameter thereof, each of said bars being of a length to connect al1 of the contact elements on one side of the drum to conductively connect all of the coils in parallel, a second set of bars diametrically-positioned on still another diameter of the drum and being of a length to connect alternate pairs of contact elements together, and plugs extending through the drum to connect opposed pairs of said last-mentioned bars to serially connect the parallelly connected pairs of coils.

2. A coil coupler for radio receiving apparatus comprising a plurality of coils, a rotary. drum of insulating material, a plurality of diametrically-arranged contact elements associated with the drum, the ends of each coil being connected to a diametrically-positioned pair of said contact elements, aplurality of plugs extending through one diameter of thedrum for conductively connecting opposed pairs of contact elements so that the coils are serially connected, a

plurality of diametrically-opposed bars posi' tioned on the surface of the. drum on another diameter thereof, eachv of said bars being of Va soy length to connect all of the contact elements prising a contact element engaging the drum,

means carried by the drum for connecting said last-mentioned contact element `with the central l portion oi' the winding regardless of the type of connection between the coils of the winding.

. 3. A coil coupler for radio receiving apparatus comprising a plurality o1' coils forming one winding of the coupler, a rotaryldrum of insulating material, a plurality of diametrically-arranged contact elements associated with the drum, the ends of each coil being connected to a diametri cally-positioned pair of said contact elements, a plurality of plugs extending through one diameter of the drum for conductively connecting opposed pairs of contact elements so that the coils are serially connected, a plurality of diametri 'cally-opposed bars positioned on the surface of the drum on another diameter thereof, each of said bars being of a length to connect all of the contact elements on one side of the drum to conductively. connect all of the coils in parallel, a second set of bars diametrically-positioned onl still another diameter of the drum and being of a length to connect alternate pairs of contact elements together, plugs extending through the drum to connect lopposed pairs of said lastmentioned bars to serially connect the parallelly -connected pairs of coils, a second `set of coils forming the other winding of the coupler, con' tact elements connected to ends thereof and engaging said drum, and means carried by the drum for connecting the coils of the second winding in series, parallel and series parallel simultaneously with the coils'of the ilrst-recited winding.

`FREDERIK MARIUS FREDERIKSEN. 

